1. Field of the Invention
The present invention relates to one-way clutches simple in structure, not calling for high precision components, and low in production cost.
2. Related Background Art
Various one-way clutches have been known in the art, finding applications in the field of automobile, in the field of agricultural machinery, and in the field of office automation equipment. Typical one-way clutches are roller and sprag one-way clutches.
An example of the conventional roller one-way clutches is now described. FIG. 10 is a schematic of a roller one-way clutch which comprises an inner race a, an outer race b relatively rotatably assembled to the inner race a, a plurality of concave recesses c which are formed on the inner periphery of the outer race b such that the concave recesses c are circumferentially spaced at predetermined pitch intervals (note that only one concave recesses c is shown in FIG. 10), a plurality of rollers d accommodated within the corresponding concave recesses c, and a spring (not shown in the figure) operable to energize the rollers d in such a direction (the counterclockwise (energizing) direction in FIG. 10) as to cause the rollers d to be caught between an outer peripheral surface e of the inner race a and an inner peripheral surface f of the outer race b.
When torque is applied to the inner race a in a direction opposite to the foregoing energizing direction (i.e., the clockwise direction in FIG. 10), the rollers d are not caught between the inner race a and the outer race b, and the inner race a is free to rotate independently of the outer race b. In other words, no torque is transmitted from the inner race a to the outer race b, as a result of which the outer race b makes no rotation. On the other hand, when torque is applied to the inner race a in the same direction as the energizing direction in which the rollers d are caught between the inner race a and the outer race b. As a result, the inter race a and the outer race b are locked together by wedging action. The input torque to the inner race a is transmitted to the outer race b. The outer race b starts rotating with the inner race a.
The above-described one-way clutch however has some drawbacks. One problem is that such a roller one-way clutch is costly because it requires high precision components and is complicated in structure.
Another problem is that if a torque in excess of the maximum transmission torque is applied to a one-way clutch, this causes severe damage to the clutch. Such damage cannot be restored by replacing components and the defective clutch must be replaced with a new one. Accordingly, in order to avoid such an incident, the provision of a torque limiter is required. The one-way clutch becomes more costly.
The maximum transmission torque cannot be changed. Accordingly, when an excessive torque is input, the input torque is output intact if it is smaller than the maximum transmission torque. It is also necessary to provide a torque limiter.
Accordingly, an object of the present invention is to provide a novel one-way clutch simple in structure, not calling for high precision components, less likely to fail to operate properly due to an excessive input torque, requiring only replacement of components even when failing to operate properly, capable of variation in maximum transmission torque, and low in cost, through the use of an improved technical structure for a belt transmission mechanism between two shafts.